Service insulator



Sept. 2, 1941. G. c. PRICE SERVICE INSULATOR Filed Dec. 8, 1937 Z/fLAST/C/ Patented Sept. 2, 1941 UNITED STATES SERVICE INSULATOR George C. Price, Parkersburg,

Porcelain Products, vporatlon of Ohio W. Va., assignor to 1110., Findlay, Ohio, a cor- Application December 8, 1937, Serial No. 178,806

1 Claim.

The invention of which the followingis a detailed description consists in improvements in service insulators of the type customarily used for providing electrical service from the service transmission lines to the building into which the electricity is to be delivered.

Insulators of this service type are widely used in the form of knobs of porcelain or like material to which lag screws or other fastenings are attached or anchored. The linemen are accustomed to mount such insulators upon a pole, tree or the wooden part of' a building without the use of special tools. The screw of the insulator is driven into the wood of the support by direct blow after which the lineman twists the knob of the insulator either by hand or by any convenient implement so that the wood screw is caused to penetrate the support and draw the base of the knob up against the surface of the support.

It is an object of my invention to provide an improved anchorage for the penetrating wood screw in the base of the knob. In this way an anchorage can be used which will have permanent size free from shrinkage and thus remain in water-tight engagement with the knob.

A further object of my invention is to give the inner recess of the knob where the screw is anchored, a good frictional surface which will effectively prevent loosening of the screw and its anchorage by hard or extreme usage.

Among the objects of my invention is the provision of means between the anchorage of the screw and the knob by which the strains will be resisted when the knob is rotated in the operation of threading the screw into the support with its consequential torsional stress.

A further object of my invention is to mount the attaching screw so firmly in the base of the knob that it will be possible to make use of a screw having deeper threads for greater holding power and greater pitch and thus quicker and easier to use.

A still further object of the invention is to provide a seal for the anchorage effective to prevent the entrance of moisture and deterioration of the bond between the anchorage and the knob. Another evident advantage of this improvement is the fact that the base of the insulator can be sealed for the two-fold purpose of protecting the shank of the screw within the knob from loosening by freezing or rusting and also preventing the access of moisture to the thread of the screw and the wood into which it is threaded and thus prevent rusting of the screw or rotting of the wood. In carrying out this feature the means used provides for an extended sealing cushion between the base of the insulator and its support whereby the space between the two parts may be partially filled in with a plastic cushion compensating for inequalities of the meeting surfaces.

To illustrate one form which this invention may take, I have shown it on the accompanying drawing in which Fig. 1 is a longitudinal section of the service insulator;

Fig. 2 is a side elevation of the same partly in section showing it attached to a support;

Fig. 3 is a horizontal transverse section on the line 33 of Fig. 1 and Fig. 4 is a bottom view showing the screw in cross-section.

It will be evident that the purposes above described for this device may be developed in a wide range of forms but the invention is illustrated by way of example to consist in an insulator body 5 formed of molded porcelain or the like. This body has the usual circular groove 6 around the lower portion of the member 5. Above this groove 6 there is a transverse hole I while a saddle groove 8 connects the opposite ends of the hole 1 over the top of the insulator body 5. The body is usually finished with a suitable glaze.

The bottom or base 9 of the body is generally unglazed. Extending inwardly and centrally of the base 9 is a cylindrical recess Ill forming a pocket or an anchor hole. The side walls of the recess l0 extend to a short distance of the plane of the base 9. At this point the recess is enlarged to provide a cavity formed partly by an open groove, channel or shouldered portion II. This groove H extends around the recess l0 and forms a cavity which is of course of greater diameter than the recess.

The inner surface of the recess I0 is finished by sanding or the provision of equivalent rough surface, the purpose being to provide a firm frictional grip on the surface for anchoring means Within the recess.

This sanded surface is coated with a thin layer of resilient asphalt or other compound [2. By this means thermal and torsional stresses will be resisted without interfering with the engagement of the parts.

A screw 13 is assembled Within the recess l0 and has its enlarged head 14 resting against the end of the recess H). The head I4 is adjacent the shank [5 which carries longitudinal ribs or other projecting portions IS on its outer surface.

sition in the recess by a body of plastic ce-" ment [8 such as Portland cement or similar material. This cement is applied and caused to harden forming a firm bond between the head of the screw and inner surface of the recess modified slightly by the protecting effect of the coated surfaces of the two portions mentioned.

A body of yieldable material l9 such as asphalt, gums or the like is poured into the groove H completely filling the area outwardly of the recess I0 and to a point beyond the plane of the base 9 as clearly shown in Figs. 1 and 2. The layer of yieldable material adheres firmly both to the body of the insulator and to the surface of the wood screw l3 and forms a yieldable mass. Insulators of the above description may be readily produced in quantity with great economy and minimum of skilled labor. The finished porcelain knobs 5 are assembled with the screws in jigs and the cement applied to the coated surfaces of the screw and recess lll thus forming a most satisfactory and durable anchorage of the screw in the base of the knob.

After the cement I8 has hardened and is thoroughly dry the cavity formed by the groove I l is filled to overflowing with a yieldable composition. In this way, the head of the screw is thoroughly protected from moisture.

An insulator so constructed lends itself readily to use in the customary manner. The lineman holding the insulator in his hand drives it with a toward the attaching screw. As shown in Fig. 2

this is prevented by the flowing characteristic of the yieldable composition l9. As the knob is screwed tight into the support the excess material in the composition l9 will be squeezed out forming 'a cushion between the base 9 and the I support. At' the same time the compound also serves to provide a satisfactory seal against further penetration of moisture. While the preferred form has been illustrated by way of example, the invention is applicableto various forms of this device within the discretion of those skilled in the art and Within the scope of the following claim.

What I claim is:

An insulator for screw-threaded attachment against a flat supporting surface, comprising an insulator body having a basal cavity and a recess of lesser diameter centrally of the cavity and extending inwardly therefrom, a screw having its shank in said recess and its point projecting outwardly from the base, a coating of yieldable material on said recess surface and on said screw shank, a body of cement filling the recess around the screw shank and a similar yieldable layer filling the cavity and overlying and merging with the material in the joints between the body of cement and the wall of the recess and screw shank.

GEORGE C. PRICE. 

